Barely visible when the weekend began, sunspot AR1619 has blossomed into a large active region more than three times as wide as Earth. Click to play a 24 hour movie recorded by NASA's Solar and Heliospheric Observatory:

So far the growing sunspot has not produced any significant flares, but the quiet is unlikely to continue if its expansion continues apace. Fast-changing magnetic fields on the sun have a tendency to reconnect and erupt. NOAA forecasters estimate a 20% chance of M-class solar flares during the next 24 hours. www.spaceweather.com